Monitoring local interconnect network (lin) nodes

ABSTRACT

The present disclosure relates to a method of monitoring Local Interconnect Network (LIN) nodes and a monitoring device performing the method. In an aspect a method of a monitoring device of monitoring a plurality of LIN buses is provided, wherein at least one LIN node is connected to each LIN bus, said plurality of LIN buses being interconnected via the monitoring device. The method comprises detecting, for each LIN bus, any dominant data being sent over said each LIN bus by a LIN node connected to said each LIN bus and routing said any dominant data received by the monitoring device over said each LIN bus to all remaining LIN buses without overwriting any dominant data sent over the remaining LIN buses.

CROSS REFERENCE

This application claims priority to European application no. 19158878.9filed Feb. 22, 2019, the entire contents of which are herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a method of monitoring LocalInterconnect Network (LIN) nodes and a monitoring device performing themethod.

BACKGROUND

The automotive industry is using message based communication protocolsbetween electronic control units (ECUs) embedded in motor vehicles. Anexample of such a protocol is Local Interconnect Network (LIN). Thisprotocol is standardized by International Standards Organization (ISO).For instance, the LIN protocol used in automotive is defined by ISOstandard ISO 17987, consisting of several sub specifications addressingdifferent parts; for example the LIN datalink layer is defined by ISO17987-3 and LIN physical layer is defined by ISO 17987-4.

An important capability in design, verification and fault tracing of LINcommunication are tools that can be used to analyse all communicationprotocol details. In particular tools that aid analysis of communicationfaults and errors. However, it is not only faults that can be ofimportance but rather finding the origin of a certain communicationevent. Analysing both expected and unexpected events can provideenhanced understanding of a LIN network. It may also be used as an earlywarning of any potential problem that may occur later on. Gathering theinformation, for instance the type of event and origin, for expected andunexpected events may be based on sampling the network communication foran amount of time or in certain operational modes. From that informationa risk analysis can be made which can aid in addressing or dismissingfurther investigation towards certain parts of a LIN network.

Conventional state of the art LIN tools provide extensive analysiscapabilities, but with ever increasing complexity of vehicle electricalsystems there is an increasing risk for systems not behaving asexpected, hence there is need for even more detailed analysiscapabilities.

An important aspect of unexpected or even expected communicationbehaviours is to determine the root cause or origin. Having thecapability to precisely determine the origin (e.g. a particular LIN ECUin a network of ECUs) of an unwanted behaviour can be especiallyvaluable as this can reduce the total effort needed to find the rootcause and make corrective actions. Another desired capability is tocharacterise an expected behaviour where some margin exist betweenactual behaviour and requirements or where requirements are looselydefined (e.g. accumulated count of error flags).

Reducing the total analysis effort usually mean that time and cost fordetecting an unexpected behaviour, determining the origin of it, makingcorrective actions, and finally verifying the problem as solved, can besignificantly reduced. Reducing time for resolving problems are oftencritical in the automotive industry.

For LIN there is at the datalink layer a possibility to detect faultyLIN frames by means of a checksum transmitted at the end of a LIN frame.A LIN node—in the form of e.g. an ECU—may determine that a receivedframe is corrupted if the checksum for the received frame does not matchwith a checksum calculated by the LIN node.

The reasons for LIN faults may be hardware or software (e.g. bugs,damaged components or even system design flaws) or environmental, suchas EMI disturbance. Depending on type of fault, this can have widelydifferent impacts on the electrical system ranging from no impact atall, slower system response, and system partly going to limp home mode,full or partial loss of system functionality or system start up- orshutdown problems. Problems can also vary over time in the same vehiclemaking them very hard to identify, reproduce, plan and implementcorrective actions and verify those actions. It can be particularlydifficult to identify and associate customer perceivable symptoms with aroot cause in the electrical system. There may also be symptoms notnoticeable by a customer but still being important or even making thevehicle not compliant to critical requirements.

Conventional LIN analysis tools that are connected in the conventionalway directly and only to a LIN bus are unable to provide some analysiscapabilities. The reason is the nature of the LIN physical layer itself.Determining several aspects about each ECU in a LIN network separatelyfrom the other ECUs may provide an improved understanding of thecommunication properties of that ECU. Having access to internalsignalling inside LIN ECUs that would support detailed analysis may bedifficult or inconvenient for several reasons. For instance, ECUs arenormally not designed for external access to internal signals, so ECUshave to be opened or modified such that internal signals can beaccessed. Further, ECUs may be difficult to access due to theinconspicuous positions in which they are mounted in the vehicle.

SUMMARY

One objective of the present invention is to solve, or at leastmitigate, this problem in the art and thus to provided an improvedmethod of monitoring a plurality of LIN nodes in the form of forinstance ECUs of a motor vehicle.

This objective is attained by a monitoring device according to anembodiment. The monitoring device is configured to receive data over aplurality of LIN buses.

If dominant data bits are received by the monitoring device over any oneor more of the plurality of LIN buses, the dominant data bits are routedover the remaining LIN buses at a voltage level interpreted by LIN nodesconnected to the buses as being dominant, but which voltage level isconfigured such that the dominant data routed over the remaining busesby the monitoring device does not overwrite dominant data sent by one ormore of the LIN nodes connected to the remaining buses.

Generally, all terms used in the claims are to be interpreted accordingto their ordinary meaning in the technical field, unless explicitlydefined otherwise herein. All references to “a/an/the element,apparatus, component, means, step, etc.” are to be interpreted openly asreferring to at least one instance of the element, apparatus, component,means, step, etc., unless explicitly stated otherwise. The steps of anymethod disclosed herein do not have to be performed in the exact orderdisclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects and embodiments are now described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 illustrates a prior art LIN bus interconnecting three LIN nodes;

FIG. 2 illustrates stipulated voltage ranges on the LIN bus forrecessive and dominant data transferred over the bus, according tostandard ISO 17987-4 and according to actual implementations used inmotor vehicles;

FIG. 3 illustrates a monitoring device 200 according to an embodimentbeing configured to monitor a plurality of LIN buses;

FIG. 4 shows a flowchart illustrating a method of the monitoring deviceof monitoring a plurality of LIN buses according to an embodiment;

FIG. 5 illustrates on a right-hand side stipulated voltage ranges on theLIN buses for recessive and dominant data of the monitoring deviceaccording to an embodiment;

FIG. 6 shows a flowchart illustrating a method of the monitoring deviceof monitoring the plurality of LIN buses according to an embodiment;

FIG. 7 illustrates an embodiment where a signal router of the monitoringdevice encodes data received from the respective LIN node;

FIG. 8a illustrates a LIN protocol handling device of the monitoringdevice according to an embodiment;

FIG. 8b illustrates a LIN protocol handling device of the monitoringdevice according to another embodiment,

FIG. 9 illustrates LIN frame header transmission performed by a firstLIN node and successful frame response transmitted by a second LIN node;

FIG. 10 illustrates LIN frame header transmission and frame responseperformed by the first LIN node;

FIG. 11 illustrates LIN frame header transmission performed by the firstLIN node and frame response transmitted by the first LIN and the secondLIN node resulting in an invalid frame response;

FIG. 12 shows a monitoring device according to a further embodiment; and

FIG. 13 illustrates a monitoring device according to another embodiment.

DETAILED DESCRIPTION

The aspects of the present disclosure will now be described more fullyhereinafter with reference to the accompanying drawings, in whichcertain embodiments of the invention are shown.

These aspects may, however, be embodied in many different forms andshould not be construed as limiting; rather, these embodiments areprovided by way of example so that this disclosure will be thorough andcomplete, and to fully convey the scope of all aspects of invention tothose skilled in the art. Like numbers refer to like elements throughoutthe description.

FIG. 1 illustrates three LIN nodes 11, 12, 13 being connected to a LINbus 14. A LIN bus is a master-slave serial communication bus. All LINnodes (embodied in the form of e.g. ECUs) in a LIN network 10 areconnected to the LIN bus. Normally one of the LIN nodes is a LIN masterand the remaining LIN nodes are LIN slaves.

Internally, each LIN node 11, 12, 13 has a bus interface circuit; a LINtransceiver 15, 16, 17. Each LIN node also has a LIN protocol controller18, 19, 20 which handles protocol bit stream reception and transmissionon data link layer according to ISO 17897. A microcontroller 21, 22, 23is connected to the respective LIN protocol controller (or frameprocessor) 18, 19, 20. The LIN controllers may optionally be a part ofthe microcontrollers.

The LIN protocol uses a serial bit stream with values 0 and 1, or alsoknown as dominant and recessive bits that make up LIN frames and otherprotocol symbols transmitted on the LIN bus 14. All LIN nodes 11, 12, 13are capable of transmitting frame responses to a frame header. The LINprotocol controller 18, 19, 20 is handling the reception andtransmission of LIN frames. The transmitted bit values 0 and 1 from theLIN protocol controller are converted in the LIN transceiver 15, 16, 17in each LIN node into two voltage levels on the LIN bus 14, which isreferred to as recessive and dominant state. That is, the recessivestate is caused by recessive data being sent over the bus, while thedominant state is caused by dominant data being sent over the bus. Thesestates relate to two voltage ranges on the LIN bus 14. For reception itis the reverse; the LIN transceiver 15, 16, 17 converts the two voltagelevels on the LIN bus 14 into suitable levels to the LIN protocolcontroller 18, 19, 20.

Each LIN node 11, 12, 13 can drive the LIN bus 14 into a series ofrecessive/dominant states, enabling a communication network according toISO 17897. The LIN protocol data link layer defines how sharing of thenetwork is performed, according to a time-division multiple access(TDMA) operation driven by a LIN master.

A LIN database is used, among other things, for associating LIN frameidentifiers to each LIN node. It can be used as a base forimplementation of the frame transmission and reception in each LIN node,as well as being used for analysis of the communication or runtimeoperation of the LIN nodes by connecting an optional LIN analysis tool.The LIN database may be seen as a lookup table; the identifier is inputand the LIN node name is obtained as a result. A LIN identifier has aunique characteristic in that it points to a certain LIN node as beingthe transmitter of a frame response for a certain frame. Further, theLIN database normally implies that any given identifier is onlyassociated to one LIN node as being the transmitter of a frame response.

In this disclosure the terms event, LIN event, and protocol event shouldbe interpreted broadly. That is; as an occurrence of a LIN protocolprocedure or mechanism defined in LIN datalink layer protocol ISO17987-3 or physical layer 17987-4. Examples are frame headertransmission, frame response transmission or network start up/wakeup.Additional examples of events are procedures that are not defined in LINdata link layer protocol 17987-3, and can constitute for instancemisbehaviour or misuse of the LIN protocol, as well as misbehaviourpreventing shutdown of the LIN network, or wakeup the LIN network.

FIG. 2 illustrates on a left-hand side stipulated voltage ranges on theLIN bus for recessive and dominant data transferred over the bus,according to standards ISO 17987-4- and 17987-7. The voltage rangesdefined by ISO 17987-4 result in no margins around the 40% and 60%levels, between transmitter voltages and receiver voltages, and may insome examples not be preferred. In practice, a slightly modified voltagerange as shown on a right-hand side is typically utilized.

The LIN bus interconnection of LIN nodes corresponds to a “wired-AND”mechanism. Recessive bits (logic 1) are overwritten by dominant bits(logic 0). In recessive state, a dominant bit from any one or more LINnodes result in a dominant bus state. As long as no LIN node is sendinga dominant bit, the bus is in the recessive state.

In FIG. 2 details are shown for expected LIN bus voltage (calledV_(BUS)) values measured between the LIN bus 14 and ground, fortransmitter part of a LIN transceiver (bus driver) and receiver part ofa LIN transceiver (bus line receiver/comparator). The transmitterallowed voltage is in intervals 251 and 241 for recessive and dominantstate while the receiver must accept intervals 252 and 242 as recessiveand dominant state respectively. The voltage of V_(BUS) is given as apercentage of the supply voltage V_(SUP) of the LIN nodes. The supplyvoltage V_(SUP) may vary for different systems, vehicles and operationalmodes of a vehicle. The voltage V_(BUS) in dominant state must bebetween 0 and 40% of the supply voltage V_(SUP) of the LIN nodes on thetransmitting LIN node output as well as on the receiving LIN node input.For a given LIN node, the actual dominant data voltage falls anywherewithin this range but is more or less fixed, with slight variation overtemperature and loading from bus termination components and impedance ofthe LIN cable.

For a population of ECUs (i.e. LIN nodes) in a single vehicle or a fleetof vehicles, the V_(BUS) dominant voltage may vary from ECU to ECUwithin the range between 0 and 40% of the supply voltage V_(SUP). Thevariation is due to several reasons like transceiver hardware productiontolerances, different transceiver brands, temperature, ageing, shifts inground reference levels, and so on. These many reasons are partly whythe allowed range from 0 to A % of voltage V_(SUP) exists, to give arobust and tolerant system even with large differences in voltage levelson the same LIN network.

A receiving ECU being compliant with ISO 17897-4- and 17897-7 mustaccept a voltage V_(BUS) from 0 to 40% of V_(SUP) as dominant. Forrecessive state, V_(BUS) is in the range from 60% to 100% of V_(SUP).For receiver voltages between 40% and 60% of V_(SUP) the resulting stateis undefined but normally there is a recessive-to-dominant anddominant-to-recessive state transition with hysteresis implemented. Ascan be seen on the right-hand side, dominant transmit is in practicecommonly selected to be from 0 to A % of V_(SUP), i.e. within the rangedenoted 248, where the value A is appropriately selected depending onthe application and may in some examples be around 5-15% of V_(BUS).

Again with reference to FIG. 1, the case when two or more LIN nodestransmit dominant state at the same time is an unexpected situation, asa frame header is normally transmitted by a LIN master, and a frameresponse is normally only transmitted by any one of the LIN master orLIN slaves. When more than one LIN node is transmitting a dominant stateat the same time it cannot always be determined for each LIN noderespectively, whether it is transmitting dominant data or recessive datathereby causing a dominant state and a recessive state on the bus,respectively, by analysing bus voltage V_(BUS), since all LIN nodes aredirectly connected to each other via the LIN bus. Determining this iseven more difficult if the dominant state output voltage from each LINnode is very close to each other so that they can not be reliablydistinguished. This is not a problem in LIN communication for the ECUsbut adds difficulty to advanced network analysis.

However, if it is required to analyse whether for instance the first LINnode 11 or the second LIN node 12 or both is actually driving the LINbus into dominant state, this cannot be determined in a reliable way bymeasuring the voltage on the LIN bus. It gets more difficult to achievea method working for all LIN buses in all vehicles including allvariables such as transceiver brand, age, temperature and so on, sincedominant state output voltage is allowed to vary within a relativelylarge range (from 0 to 40% of V_(SUP)) and most likely there will be adistribution of voltages where a few ECUs have less V_(BUS) dominantdrive capability than others ECUs on the same LIN bus.

Further, by analysing the current that each LIN node drive into the LINbus while at the same bit time transmitting dominant data is also achallenge since in principal it is only the LIN node with the highestV_(BUS) dominant drive capability that force current. Alternatively itis only the LIN nodes with highest V_(BUS) dominant drive capabilitythat actually force a reliably measureable current to flow out of thetransceiver.

If it is required to analyse whether for instance the first LIN node 11or the second LIN node 12 or both is actually driving the LIN bus intodominant state, this cannot be determined in a reliable way by measuringthe current flow to/from the transceiver 15, 16 and the LIN bus.

FIG. 3 illustrates a monitoring device 200 according to an embodimentbeing configured to monitor LIN nodes 100, 110, 120 being connected toLIN buses 105, 115, 125 connected between the monitoring device 200 andthe respective LIN node 100, 110, 120.

At least two LIN buses are connected to the monitoring device 200, whereat least one LIN node is connected to each LIN bus. However, a greaternumber of LIN nodes may be connected to each LIN bus. Further, themonitoring device 200 is configured to transfer signals carried over anyone of the LIN buses to the remaining LIN buses. Thus, signalstransferred over the first LIN bus 105 is carried over the second LINbus 115 and the third LIN bus 125, signals transferred over the secondLIN bus 115 is carried over the first LIN bus 105 and the third LIN bus125, and so on.

It is noted that a number of LIN nodes may be connected to a bus. If acertain LIN node is to be monitored, then that LIN node should be theonly node connected to a bus. However, it may be envisaged that a groupof LIN nodes is to be monitored in a scenario where it is not necessaryto distinguish between individual LIN nodes in the group. For instance,it may be desirable to analyse a group of LIN nodes originating from thesame manufacturer. If so, the group of LIN nodes can all be connected tothe same LIN bus.

As in FIG. 1, the LIN nodes 100, 110, 120 comprise a LIN transceiver101, 111, 121, a LIN protocol controller 102, 112, 122 and amicrocontroller (not shown in FIG. 3). As is understood, a LINtransceiver and a LIN protocol controller is required for any deviceconfigured to be connected to a LIN bus. In this example, as in FIG. 1,a LIN controller is part of a micro-controller. In another example, theLIN controller is not part of a micro-controller but is a separate partin a LIN node.

The monitoring device 200 according to an embodiment comprises a LINtransceiver 201, 211, 221 connecting to the respective LIN bus 105, 115,125.

Further, the monitoring device 200 comprises a signal router 202configured to route the LIN signals transmitted over any LIN bus to theremaining LIN buses. For instance, any LIN signal transmitted by firstLIN node 100 is received by the first LIN transceiver 201 and thenrouted via the signal router 202 to the second LIN transceiver 211 andthe second LIN node 110 as well as to the third LIN transceiver 221 andthe third LIN node 120. While the monitoring device 200 is illustratedas a hardware device in FIG. 3, it may also be envisaged that the devicecan be implemented as a simulation model for simulating behaviour of LINnodes in the form of e.g. ECUs.

The routing of signals by the signal router 202 is performed since theLIN nodes 100, 110, 120 under test should display the same behaviour asif they were connected to a single LIN bus as shown in FIG. 1. In otherwords, all of the LIN buses 105, 115, 125 should be exposed to the samedata.

Hence, assuming that a “real-world” scenario is to be tested using thesetup of FIG. 3. One or more of the LIN nodes 100, 110, 120 may betriggered to perform a selected action resulting in signals occurring onthe LIN buses, i.e. LIN data being sent from one of the LIN nodes 100via the bus 105 to the monitoring device 200 is routed to the remainingLIN nodes 110, 120 over the respective bus 115, 125.

Reference will further be made to FIG. 4 showing a flowchartillustrating a method of the monitoring device 200 of monitoring theplurality of LIN buses 105, 115, 125 according to an embodiment.

Hence, the monitoring device 200 monitors, for each of the LIN nodes100, 110, 120, any event occurring on the LIN buses 105, 115, 125. Thatis, any data sent via the LIN bus of each LIN node is monitored by themonitoring device 200. In this particular example, it is assumed thatthe first LIN node 100 sends data over the first LIN bus 105 to thefirst LIN transceiver 201 of the monitoring device 200.

In order to re-create the situation where all the LIN nodes 100, 110,120 are connected the LIN bus as previously has been illustrated withreference to FIG. 1, the monitoring device 200 receives the LIN data viathe first LIN transceiver 201, performs a detection process in step S101(to be described in detail below) and routes in step S102 the LIN datavia signal RXD′ over path 204 to the signal router 202 and further onvia a) signal TXD′ over path 213 to the second LIN transceiver 211 overthe second LIN bus 115 to the second LIN node 110, and b) signal TXD′over path 223 to the third LIN transceiver 221 over the third LIN bus125 to the third LIN node 120.

Advantageously, the LIN nodes 100, 110, 120 are analysed in anon-intrusive manner. The LIN nodes 100, 110, 120 are no longerelectrically directly connected to each other on a physical layer, butremains connected on a datalink layer. It is to be noted that for anynew vehicle, the monitoring device 200 may be implemented from scratchin the manner illustrated in FIG. 3, while for an existing vehicleimplementing the prior art LIN bus of FIG. 1, the bus would have to be“broken up” such that the monitoring device 200 can be connected asshown in FIG. 3.

Thus, datalink timing between the LIN nodes remains unaffected and theLIN nodes share all transmitted recessive and dominant bits exactly asif the LIN nodes were still directly connected to each other via asingle LIN bus. This is applicable for all possible events, includingevents that are outside the defined events in the LIN protocol.

Hence, with the routing of data over the remaining LIN buses 115, 125 tothe remaining LIN nodes 110, 120, the monitoring device 200 does notaffect the LIN network in a manner such that the behaviour of the LINnodes changes; the LIN nodes 100, 110, 120 will act as if they areconnected to a single LIN bus.

However, while the monitoring device 200 receives data over the RXD′wire 204 from the first LIN node 100, the event detection device 200 maysimultaneously send data, for instance originating from the second LINnode 110, to the first LIN node 100 via TXD′ wire 203.

This implies that each LIN bus 105, 115, 125 may be driven dominant byboth the LIN nodes (in this example the first LIN node 100) and also bythe monitoring device 200 at the same time, since the monitoring device200 routes data received over any one of the LIN buses to the remainingLIN buses. Driving a LIN bus dominant from the LIN node side and fromthe monitoring device side suggests a potential problem, in that themonitoring device 200 cannot determine why the LIN bus 105 is dominant.That is, whether it is because the first LIN data 100 is transmittingdominant data bits or because the monitoring device 200 itself istransmitting dominant data bits.

If not resolving this critical problem, the monitoring device 200 maylatch up and never release the dominant state to which it has driven theLIN bus 105. The latch up problem would occur as soon as at least twoLIN nodes out of LIN nodes 100, 110, 120 transmit dominant data bits,thereby causing a dominant state, at the same time.

Thus, in step S101, the monitoring device 200 detects if any dominantdata bits are being sent by any LIN node, 100, 110,120 over therespective LIN bus 105, 115, 125. In this particular example, themonitoring device 200 detects that dominant data is being sent over thefirst LIN bus 105 by the first LIN node 100.

Further, if the first LIN node 100 is the one sending the dominant databits, these dominant bits are routed in step S102 to the second LIN node110 and the third LIN node 120, in a manner such that the routeddominant bits do not overwrite any dominant bits transferred by thesecond LIN node 110 and the third LIN node 120 over the LIN buses 115,125.

Advantageously, any dominant data received by the monitoring device 200over any LIN bus 105, 115, 125 is routed to the LIN nodes 100, 110, 120connected to the remaining LIN buses 105, 115, 125.

As an example, dominant data received from the first LIN node 100 overthe first LIN bus 105 is routed to the second LIN node 110 over thesecond LIN bus 115 and to the third LIN node 120 over the third LIN bus125.

Further, any dominant data simultaneously received by the monitoringdevice 200 for instance from the second LIN node 110 over the second LINbus 115 is routed to the first LIN node 100 over the first LIN bus 105and to the third LIN node 120 over the third LIN bus 125, in a mannersuch that the dominant data received from the first LIN node 100 to notoverwrite the dominant data received from the second LIN node 110, andvice versa.

Hence, the above described latch up problem is advantageously overcome.

With reference to FIG. 5, in an embodiment, the dominant data bitdetection is performed as will be described in the following. In FIG. 5,the voltage diagram on the left-hand side is identical to thatpreviously illustrated on the right-hand side in FIG. 2. Hence, the LINnodes 100, 110, 120 are all configured to output data where a voltageV_(BUS) between the LIN bus 14 and ground potential is in a range from 0to A % of V_(SUP), where A is a value lower than 40% of V_(SUP).

However, the voltage diagram on the right-hand side illustrates voltagelevels which the monitoring device 200 is configured to comply withaccording to an embodiment. In the voltage diagram on the right-handside, it is illustrated that the monitoring device 200 is configured tooutput dominant data bits to the LIN nodes at a voltage level notexceeding a maximum receive voltage level stipulated by the LIN standardfor dominant data bits, i.e. not exceeding 40% of V_(SUP), but notoverlapping with the voltage level with which the LIN nodes areconfigured to output dominant data bits, i.e. at least B % of V_(SUP).That is, the dominant data bits are outputted by the monitoring device200 at a voltage level falling into range 244, where the range 244 doesnot overlap with the range 248. However, the range 244 is configured tooverlap with range 242, such that the LIN nodes will perceive a voltagein range 244 as dominant data being sent by the monitoring device 200.

Further, the monitoring device 200 is configured to receive dominantdata at a voltage level at least being in the range 248 with which theLIN nodes 100, 110, 120 are configured to output dominant data, i.e. inthe range from 0 to A % of V_(SUP), even though dominant receive rangeof the monitoring device 200 may be configured to be in range 245, i.e.from 0 to just below B % of V_(SUP). For the monitoring device 200, thedominant transmit range 244 should not overlap with the dominant receiverange 245, since that would cause a latch-up on the LIN bus.

To comply with recessive receive stipulated in ISO 17879-4 and 17897-7,range 246 should at least overlap with range 251, but preferably alsowith range 252 (but not with range 248), even though the range 246 couldextend over the voltage span illustrated in FIG. 5. Further, themonitoring device 200 should interpret its own dominant transmit datavoltage range 244 as recessive receive, implying that range 246 overlapswith range 244. The boundary range between ranges 245 and 246 is denoted247.

As a result, the monitoring device 200 will advantageously detect adominate state driven by any of the LIN nodes 100, 110, 120 in case thevoltage on the buses 105, 115, 125 is from 0 to A % of V_(SUP), sincerange 248 overlaps with range 245, while the monitoring device 200 usesa voltage in the range 244 (which does not overlap with the range 248)to transmit dominant bits, i.e. to cause a dominant state on the LIN bus14. That is, the LIN nodes 100, 110, 120 output dominant data at avoltage level between 0 and A % of V_(SUP) while the monitoring device200 outputs dominant data at a voltage level between B and 40% ofV_(SUP), where B should exceed A.

In one embodiment there is an advantage of having the voltage A % and B% clearly separated. Such separation accomplishes a margin betweentransmitted dominant voltage 248 and received dominant voltage 245,which adds robustness to the system.

The receiver dominant detection voltage range of the monitoring device200 (defined by voltage interval 245) is configured not to overlap itstransmitter dominant voltage interval 244. Further, the V_(BUS) voltagewhere transition recessive-to-dominant and transitiondominant-to-recessive occur and is provided by transceiver 201, 211, 221output signals RXD, lies between voltage intervals 245 and 246 (i.e. theboundary range 247).

Reference will further be made to FIG. 6 showing a flowchartillustrating a method of the monitoring device 200 of monitoring theplurality of LIN buses 105, 115, 125 according to the embodimentdiscussed with reference to FIG. 5.

As can be seen, if the monitoring device 200 detects that the voltage ofthe data sent over the first LIN bus 105 from the first LIN node 100 isin the range from 0 to A % of V_(SUP) in step S101, the correspondinglydominant data received from the first LIN node 100 is routed to thesecond LIN node 110 and the third LIN node 120 over the second and thirdLIN bus 115, 125 at a voltage level between B % and 40% of V_(SUP),where B>A in step S102 a. Advantageously, this avoids overwriting anydominant data simultaneously being written to the second LIN bus 115 bythe second LIN node 110 and/or to the third LIN bus 125 by the third LINnode 120, since the outputted LIN node dominant data always is at alower voltage level than the outputted monitoring device dominant data,i.e. there is no overlap between ranges 244 and 248.

According to ISO 17987-4, the LIN transceiver for a LIN master and LINslave is internally arranged with a pull-up resistor which willpassively pull-up the bus voltage V_(SUP) to be well above 60%, when allLIN nodes are driving at a recessive state. A LIN node driving dominantstate will actively by means of e.g. a transistor actively drive thevoltage to a lower voltage level. The LIN node that have the capabilityto actively drive, or pull down, the bus voltage to the lowest voltageV_(SUP) will be the LIN node determining the resulting bus voltageV_(SUP).

In another scenario, if the data over the first LIN bus 105 is not inthe range from 0 to A % of V_(SUP) in step S101—and the monitoringdevice 200 is not sending dominant data over the first LIN bus 105,thereby indicating that dominant data is not being sent by the secondLIN node 110 and/or by the third LIN node 120—recessive data is receivedfrom the first LIN node 100, which is routed in step S102 b from thefirst LIN node to the second LIN node and the third LIN node at avoltage level between 60% and 100% of V_(SUP). It should be noted thatif any one of the other LIN nodes 110, 120, for instance the second LINnode 110, would transmit dominant data, that particular dominant datawould be routed to the first LIN node 100 and the third LIN node 120,and any recessive data from the first LIN node 100 would thus beoverwritten.

FIG. 7 illustrates a further embodiment, where the signal router 202 ofthe monitoring device 200 encodes data received from the respective LINnode.

Hence, data received from the first LIN node 100 via the first LINtransceiver 201 with signal RXD′ over path 204 is combined in a firstencoder 216 with data received from the third LIN node via the third LINtransceiver 221 with signal RXD′ over path 224. As can be seen in theupper table, if any combined bits of the received data is 0, then theoutput of the first encoder is 0. As a consequence, the signal router202 will output dominant data, i.e. a 0, indicating a dominant statewith the signal TXD′ over path 213, which 0 the second LIN transceiver211 converts to a voltage in the range from B % to 40% of V_(SUP) andoutputs to the second LIN node 110 as soon as any one or both of thefirst LIN node 100 and the third LIN node 120 outputs dominant bits(i.e. a 0 represented by a voltage in the range B % to 40% of V_(SUP)).

Correspondingly, a second encoder 206 receives data from the second LINnode 110 and the third LIN node 120 and outputs a 0 to the first LINnode 100 if any one or both of the second LIN node 110 and the third LINnode 120 transmits a 0, i.e. a dominant bit, while a third encoder 226receives data from the first LIN node 100 and the second LIN node 110and outputs a 0 to the third LIN node 120 if any one or both of thefirst LIN node 100 and the second LIN node 110 transmits a 0.

As can be concluded, if data received from any one of the LIN nodes overthe LIN buses indicates a dominant state in the form of a 0 representedby a voltage in the range from 0 to A % of V_(SUP), the encoders willoutput a dominant bit in the form of a 0, which the associated LINtransceivers transmits to the remaining LIN nodes in the form of avoltage in the range from B % to 40% of V_(SUP).

As further can be seen in FIG. 7 (and also in FIG. 3), the monitoringdevice 200 monitors any data transmitted by the LIN nodes 100, 110, 120via the respective signal RXD′ over paths 204, 214, 224.

In a further embodiment, also described with reference to FIG. 7, thesignal router 202 comprises a fourth encoder 205, where data receivedfrom the first LIN node 100 via the first LIN transceiver 201 with thesignal RXD′ over path 204 is combined with data received from the secondLIN node 110 via the second LIN transceiver 211 with the signal RXD′over path 214 and with data received from the third LIN node 120 via thethird LIN transceiver 221 with the signal RXD′ over path 224. Again, ascan be seen in the lower table, if data received from any one of the LINnodes indicates a dominant state in the form of a 0 represented by avoltage in the range from 0 to A % of V_(SUP), the fourth encoder willoutput a dominant bit in the form of a 0 over wire 210 a. The signalRXD″ sent over path 210 a is routed to a LIN protocol handling device230, as will be discussed in the following.

FIG. 8a illustrates the LIN protocol handling device 230 according to anembodiment, which functionally comprises a LIN protocol controller 231,or frame processor, which LIN protocol handling device 230 utilizes thesignal RXD″ carried over path 210 a.

FIG. 8b shows the LIN protocol handling device 230 utilizing analternative signal RXD′″ carried over path 210 b according to anembodiment.

Path 210 b serves the same purpose as the signal path 210 a; to providea combined signal where data being carried over the LIN buses 105, 115,125 is routed to the LIN protocol handling device 230. Since themonitoring device 200 routes data from the second LIN bus 115 and thethird LIN bus 125 to the first LIN bus 105, the data on the first LINbus 105 (or that on any bus) represent combined data from the first,second and third LIN nodes 100, 110, 120. A transceiver 215 is connectedto LIN bus 105 and the RXD wire 210 b. The transceiver 215 has the samevoltage ranges for reception as the LIN Nodes 100,110,120, which areaccording to ISO 17987.

In one example the transceiver 215 only uses its receiver part while thetransmitter part is not used and therefore the transmitter input TXDsignal is permanently tied to a recessive state. In another example thetransceiver 215 is instead a bus line receiver and there is notransmitter or TXD signal provided.

With reference to FIGS. 8a and 8b , the signal 210 b or alternativelythe signal 210 a output from the fourth encoder 205 (discussed withreference to FIG. 7) which combines signals from all the LIN nodes 100,110, 120 is supplied to the LIN protocol controller 231. The LINprotocol controller 231 monitors all events from each LIN node as onecomposite signal 210 a (or 210 b), which signal 210 a (or 210 b)represents what each LIN node 100, 110, 120 actually is seeing on therespective LIN bus 105, 115, 125 (corresponding to the data beingtransferred over the LIN bus 14 of FIG. 1), in this particular examplethe data sent by the first LIN node 100 as previously discussed.Further, the LIN protocol controller 231 is capable of interpreting thedata received with signal 210 a or 210 b in the context of a LIN frame.Thus, the LIN protocol controller 231 maps the data received with signal210 a or 210 b into a LIN frame (or a plurality of LIN frames). The LINprotocol controller 231 has no TXD path back to any of the transceivers201, 211, 221 or 215, or encoder 205. This is intentional since it mustnot affect the data that it shall monitor.

In one embodiment the transceivers 201, 211, 221 does not support beingset to standby mode and continuously pass all symbols like framesheaders, frame response and wakeup signals and any dominant state notrecognized as a valid LIN protocol symbol to LIN protocol controller231. The LIN protocol controller 231 is configured to recognize wakeupsignals according to ISO 17987-3.

Further, any one of LIN nodes 100, 110, 120, can be a LIN master, andthe remaining LIN nodes can be LIN slaves. The monitoring device 200advantageously handles the LIN master being connected to any of the LINbuses 105,115,125. If more than one LIN master would be connected, e.g.the first LIN node 100 being a LIN master and the second LIN node 110also being a LIN master, this unusual system configuration could beidentified by the LIN monitoring device 200.

The LIN protocol controller 231 is in an embodiment capable of encodingthe data received over paths 210 a or 210 b into LIN frame headers andLIN frame responses as specified in the LIN standard. Examples of suchLIN frames will be given hereinbelow. These LIN frames may be providedfor display to an operator of the monitoring device 200 via path 231 a.

Further, the LIN protocol controller 231 is in an embodiment capable ofmapping events indicated by the LIN protocol controller to specific LINnodes, and providing this information via paths 232 a, 232 b, 232 c suchas for instance “LIN frame header received from the first LIN node” viapath 232 a, “LIN frame response received from the second LIN node” viapath 232 b, etc. Any LIN frame format may be used.

Included are also the TXD signals 103, 113, 123 from the LIN nodes 100,110, 120. Those TXD signals are not available to the monitoring device200. However, their waveforms are recreated by the transceivers 201,211, 221 in the monitoring device 200 as signals 204, 214, 224 and areshown for illustrational purposes.

FIG. 9 illustrates LIN frame header transmission performed by the firstLIN node 100 and LIN frame response transmitted by the second LIN node110, and no transmission by the third LIN node 120.

As can be seen in FIG. 9, a LIN frame 301 consists of a so called frameheader and a frame response. A BREAK field is used to activate all LINslaves (i.e. the second LIN node 110 and the third LIN node 120) tolisten to the following parts of the header transmitted by a LIN master(i.e. the first LIN node 100 in this case). Hence, the BREAK field actsas a start-of-frame indicator. The header further includes a SYNC fieldused by the slave nodes for clock synchronization. The IDENTIFER definesa specific message address. Thereafter, the frame response part of theLIN frame commences, which is sent by any one of the slave nodes or themaster node, the message response consisting of N bytes of DATA and aCHECKSUM field.

It is noted that in FIGS. 9-11, for illustrative purposes, a part of theDATA field of the respective LIN frame 301, 311, 321 (and thecorresponding sections of the remaining signals) has been compressed intime as this field may contain up to 64 bits.

If at the time of detection of the BREAK field any of the RXD′ signalsover paths 204, 214, 224 is 0 (i.e. dominant), then the correspondingLIN node is identified as being the LIN node transmitting the LIN frameheader 302, 304, 306 comprising the data transported with signals 210 aor 210 b. While both the RXD′ signal carried over path 214 for thesecond LIN node 110 and the RXD′ signal carried over path 224 for thethird LIN node 120 is 1 (i.e. recessive), the RXD′ signal carried overpath 204 for the first LIN node 100 is indeed 0. Thus, the first node100 must be the source of the data received over paths 210 a, 210 b, inthis case a LIN master.

With reference to the voltage V_(BUS) of the signals carried over theLIN buses 105, 115, 125, in this example the first LIN node 100 drivesthe bus into a dominant state resulting in a V_(BUS) in the range 248(cf. FIG. 5). The monitoring device 200 will thus conclude that it isthe first LIN node 100 that sends the dominant data bit over the firstLIN bus 105, and as a result route that dominant bit to the second andthe third LIN node 110, 120 via paths 213, 223, respectively, over thesecond and third LIN bus 115, 125 at a V_(BUS) in the range 244.

The LIN protocol controller 231 will then encode the data sent by thefirst LIN node 100 and received over path 210 a or 210 b into a LINframe headers until all headers fields BREAK, SYNC and IDENTIFIER areencountered.

As can be seen, at the time of the DATA 1 through DATA-N and CHECKSUMfields being encountered in the frame response, LIN bus combinationsignal 210 a or 210 b indicates dominant data being transmitted over theLIN buses, and the LIN protocol controller 231 detects from paths 214,224 only the second node 110 transmitting dominant data therebysuccessfully completing the LIN frame transmission, indicated with 305.

Again, with reference to the voltage V_(BUS) of the signals carried overthe LIN buses 105, 115, 125; at the time of frame response, in thisexample the second LIN node 110 drive the bus into a dominant stateresulting in a V_(BUS) in the range 248. As a result, the monitoringdevice 200 will route a dominant bit to the first LIN node 100 via path203 over the first LIN bus 105 at a V_(BUS) in the range 244.

FIG. 10 illustrates frame transmission similar to FIG. 9, but in thiscase it is the first LIN node 100 that transmits both LIN frame headerand LIN frame response. The first LIN node 100 is a LIN master, as theframe header is transmitted by the first LIN node 100. Theidentification as regards which LIN node is transmitting the frameheader is the same is that of FIG. 9.

With reference to the voltage V_(BUS) of the signals carried over theLIN buses 105, 115, 125, in this example the first LIN node 100 drivesthe bus into a dominant state resulting in a V_(BUS) in the range 248(cf. FIG. 5). The monitoring device 200 will thus conclude that it isthe first LIN node 100 that sends the dominant data bit over the firstLIN bus 105, and as a result route that dominant bit to the second andthe third LIN node 110, 120 via paths 213, 223, respectively, over thesecond and third LIN bus 115, 125 at a V_(BUS) in the range 244.

The LIN protocol controller 231 will then encode the data sent by thefirst LIN node 100 and received over path 210 a or 210 b into a LINframe header until all headers fields BREAK, SYNC and IDENTIFIER areencountered.

As can be seen, at the time of the DATA 1 through DATA-N and CHECKSUMfields being encountered in the frame response, LIN bus combinationsignal 210 a or 210 b indicates dominant data being transmitted over theLIN buses, and the LIN protocol controller 231 detects from paths 214,224 only the second node 110 transmitting dominant data therebysuccessfully completing the LIN frame transmission, indicated with 313.

Again, with reference to the voltage V_(BUS) of the signals carried overthe LIN buses 105, 115, 125; at the time of frame response, in thisexample the first LIN node 100 drive the bus into a dominant stateresulting in a V_(BUS) in the range 248. As a result, the monitoringdevice 200 will route a dominant bit to the second LIN node 110 via path213 over the second LIN bus 115 at a V_(BUS) in the range 244.

FIG. 11 illustrates a slightly more complex scenario in the form of aLIN frame header transmission performed by the first LIN node 100 andframe response transmitted by the first LIN 100 and the second LIN node110, resulting in an invalid frame response. A frame response isexpected to be transmitted by only one LIN node. Again, up until theframe header of the LIN frame is encountered, the behaviour is the sameas that described with reference to FIGS. 9 and 10. Hence the first LINnode 100 is identified as being the LIN node transmission the LIN frameheader.

However, after the frame header both the first LIN node 100 and thesecond LIN node 110 start to transmit a frame response. For simplicity,the byte fields of the frame responses are exactly aligned in time sothey are transmitted synchronously. In another example, the byte fieldsof the first LIN node 100 and second LIN node 110 could be transmittedwith slightly different delays relative to each other which would resultin invalid byte fields DATA1 trough CHECKSUM.

Due to the wired-AND nature of the LIN transceivers 101, 111, 121 in theLIN nodes and the LIN transceivers 201, 211, 221 in the monitoringdevice 200, the same bits transmitted by different LIN nodes but withdifferent bit values will result in a logical 0 on buses 105, 115,125for that bit. Hence, a transmitted bit with logical 1 will beoverwritten by a bit with logical value 0, with the resulting value 0 onall LIN buses. That will also occur on the CHECKSUM byte fieldstransmitted by the first LIN node 100 and by the second LIN node 110.For simplicity, in FIG. 11 the exact bit values in each byte fields DATA1 trough CHECKSUM are not shown, but the overwriting as such of logical1 into logical 0 is highlighted on bus-signals 105,115,125. Overwritingof data bits in byte fields is not a normal expected part of LIN frameheader or LIN frame response transmission or and is advantageouslydetected by the LIN monitoring device 200 as an error event.

As a result, any LIN node and also the LIN protocol controller 231receiving this LIN frame will interpret the CHECKSUM as being incorrectfor the DATA 1 trough DATA N fields. The LIN protocol handling devicewill receive the DATA 1 trough CHECKSUM fields from the combined RXDsignal 201 a or 210 b. However the frame response byte fields DATA 1trough CHECKSUM will appear as valid byte fields if judged only by theV_(BUS) bus voltages, and not considering the validity of the CHECKSUM,on all buses 105,115,125.

As is understood, numerous use cases may be envisaged. In the following,a brief list of use cases is discussed.

-   -   a. A LIN master transmits a LIN frame header and it needs to be        determined which LIN node is the LIN master.    -   b. A LIN slave transmits a LIN frame response and it needs to be        determined which LIN node is transmitting the LIN frame        response.    -   c. More than one LIN slave transmit a LIN frame response and it        needs to be determined which LIN slave is transmitting the frame        responses. If more than one LIN slave transmit frame response        this will likely result in that the response becomes invalid,        for several reasons, e.g. simply by checksum error.    -   d. A LIN slave transmits a wakeup signal and it needs to be        determined which LIN slave is transmitting the wakeup signal.    -   e. More than one LIN master is connected in the LIN network,        which is normally unexpected. LIN network communication thus        behaves erratic, and it needs to be determined why there is        erratic communication.    -   f. A LIN node is disturbing the bus which causes frame reception        failure and it needs to be determined which LIN node is        disturbing the bus.    -   g. A LIN network is woken up. This can be due to a LIN master        transmitting LIN frame header or a LIN slave transmitting a        wakeup signal and it needs to be determined why the LIN network        is woken up.

FIG. 12 shows a monitoring device 200 according to an embodimentcomprising the signal router 202 and the LIN protocol controller 231previously discussed. However, in this embodiment, the monitoring device200 further comprises a memory 240 where all or a selected part ofmeasurements being performed can be stored and analysed. For instance,statistics may be provided to an operator. Further, individual signalse.g. carried over paths 204, 214, 224, 210 a, Or 210 b, may be storedfor analysis by an operator or a computer.

Further, the monitoring device 200 may be provided with a display 300where any signal or detected events in the monitoring device 200 may bedisplayed. In this example, the LIN frames over path 231 a and eventsover path(s) 232 are provided for display to an operator of themonitoring device 200.

Further, the monitoring device 200 comprises one or more processingunits 250 in which the functionality of the monitoring device 200 may beimplemented. Typically, all functionality of the monitoring device 200(except for the display 300) may be carried out by such processingunit(s) 250, such as that of the transceivers 201, 211, 221, the signalrouter 202, the LIN protocol controller 231, etc.

The steps of the method of the monitoring device 200 for monitoring aplurality of LIN buses according to embodiments may thus in practice beperformed by the processing unit 250 embodied in the form of one or moremicroprocessors arranged to execute a computer program 260 downloaded toa suitable storage medium 270 associated with the microprocessor, suchas a Random Access Memory (RAM), a Flash memory or a hard disk drive.The processing unit 250 is arranged to cause the monitoring device 200to carry out the method according to embodiments when the appropriatecomputer program 260 comprising computer-executable instructions isdownloaded to the storage medium 270, being e.g. a non-transitorystorage medium, and executed by the processing unit 250. The storagemedium 252 may also be a computer program product comprising thecomputer program 260. Alternatively, the computer program 260 may betransferred to the storage medium 270 by means of a suitable computerprogram product, such as a Digital Versatile Disc (DVD) or a memorystick. As a further alternative, the computer program 260 may bedownloaded to the storage medium 270 over a network. The processing unit250 may alternatively be embodied in the form of a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield-programmable gate array (FPGA), a complex programmable logicdevice (CPLD), etc.

In one embodiment, the LIN transceivers of 201, 211, 221, are IntegratedCircuit (IC) packaged devices with a transmitter (bus driver) and areceiver (bus line receiver) in the same IC package. In anotherembodiment the transceivers may be constructed by a plurality of passivecomponents and by linear or digital semiconductor components.

In an embodiment, the LIN transceivers of 201, 211, 221 can have atleast two configurations of the bus driver output voltage and buscomparator input thresholds, where one selected configurations of aplurality of configuration is in operation. For example, oneconfiguration can be according to FIG. 2, and another configuration canbe according to right side of FIG. 5. There is provided a configurationselection input, in one example in the form of digital selection inputpin, in another example there is a serial peripheral interface (SPI)bus.

In one embodiment at least two LIN buses of 105, 115, 125, and at leasttwo transceivers of 201, 211, 221, and the signal router 202 is part ofa LIN bus repeater or LIN bus extender.

In a further embodiment two of LIN buses 105, 115, 125 and two oftransceivers 201, 211, 221 are used with a simplified signal router 202.The signal router does not need to have encoder 206, 216, 226. Encoder205 is an encoder with two inputs, one being RXD′ output 204 of a firsttransceiver and one being RXD′ output 214 of a second transceiver. Thesignal routing is simplified compared to FIG. 7; RXD′ output 204 of afirst transceiver is directly connected to a TXD′ input 213 of a secondtransceiver, and connected directly to a LIN protocol handling device230. RXD′ output 214 of a second transceiver is directly connected to aTXD′ 203 of a first transceiver, and connected directly to a LINprotocol handling device 230.

In a further embodiment at least LIN buses 105, 115, 125, and at leasttransceivers of 201, 211, 221, and the signal router 202 are part of aLIN active star coupler.

In a further embodiment some or all parts of monitoring device 200 ispart of a digital storage oscilloscope with serial bus protocoldecoding.

An approach in LIN analysis is to passively and non-intrusively monitorthe LIN nodes. This may require extended monitoring time in order togather sufficient data about the LIN nodes. However, time available formonitoring may be limited and not enough in some scenarios. In a systemof LIN nodes, there may be additional conditions caused by other nodesof the system, which affect node operation. Those conditions may notnecessarily occur if performing a standalone LIN node test during e.g.LIN conformance verification. Therefore, in an embodiment, an approachis to actively generate and transmit signals over the LIN bus causing adesired result, and to monitor any LIN nodes in operation, e.g. errorconditions of the LIN nodes.

LIN nodes receiving the exact same bit-stream of LIN data frames handleerrors in the data link layer in the same way.

Conversely, LIN nodes not receiving the exact same bit-stream of LINdata frames may handle errors in the data link layer in different ways.This may happen in e.g. harsh electrical environments such as e.g. motorvehicles, or because of a compromised bus topology, due to LIN bussignal integrity problems. Hence, a certain LIN ECU may or may not bethe only LIN node to detect an error.

To evaluate a specific LIN node data link layer operation whiledetecting errors in a LIN system, two main scenarios are of interest:

-   -   i. the specific LIN node is the only node to detect a data link        error and perform a predetermined action in application layer.        Other LIN nodes do not detect an error, and    -   ii. at least one other LIN node detects a data link error and        performs a predetermined action in application layer.

LIN nodes that do not receive the exact same application signals in adata field of a LIN data frame may handle manipulated signals indifferent ways or at different instants of time of associated bits inthe stream.

To evaluate a specific LIN node application layer operation whilereceiving manipulated signals in a LIN system, two main scenarios are ofinterest:

-   -   i. the specific LIN node is the only node to receive a        manipulated signal in a data field, while other LIN nodes        receive non-manipulated signals, and    -   ii. all LIN nodes receive a manipulated signal in a data field.

FIG. 13 illustrates a monitoring device 200 according to an embodimentcomprising a first bit-stream manipulation module 281 connected in theRXD′ path 204 and a second bit-stream manipulation module 291 connectedin the TXD′ path 203 between a transceiver 201 and a signal router 202.The modules 281, 291 are controlled to handle bit manipulation of LINframe to and from one or more LIN nodes 100, 110, 120 (not shown in FIG.13).

The first bit-stream manipulation module 281 may optionally becontrolled to modify bits in a received LIN data frame from the LINtransceiver 201 and the first LIN node 100 before passing the frame tothe signal router 202. The activation or deactivation of manipulationmay be based on a LIN frame identifier in an arbitration field, i.e. acertain bit position in a LIN frame. The manipulation may introduce adata link error, e.g. a checksum error. This manipulation will cause thesecond and third LIN nodes 110, 120 to receive manipulated LIN frames,and the second and third LIN nodes 110, 120 are expected to detecterror. The first bit-stream manipulation module 281 may be equipped witha manipulation configuration memory, and/or a software executableinstruction or similar.

The second bit-stream manipulation module 291 may optionally becontrolled to modify bits in a received LIN data frame from the signalrouter 202 before passing the frame to the LIN transceiver 201 and thefirst LIN node 100. The manipulation can be based on detecting aspecific value of a received identifier, i.e. a certain bit position ina LIN frame. The manipulation may introduce a data link error e.g. achecksum error. This manipulation will cause the first LIN node 100 toreceive manipulated LIN frames, and the first LIN node 100 is expectedto detect errors.

LIN frames contain a cyclic redundancy checksum so that a receiver ofthe frames can validate the received frame as having no data link layererrors and therefore being correctly received or alternatively havingerrors (there is an eight-bit checksum field). This results in a certaindegree of tolerance to some minor modification of the bit-stream(including e.g. data field) for which the checksum is calculated, wherethe resulting modified data field will result in an identical checksumas before the modification. However, this is in most situationsunlikely. A majority of possible modifications of only a data field of aLIN frame will have as a consequence that such frame will be renderedinvalid (and cause a checksum error), unless the checksum is properlymodified as well.

The first bit-stream manipulation module 281 may optionally becontrolled to modify bits in a data field and a checksum field of areceived LIN frame from the LIN transceiver 201 and the first LIN node100 before passing the manipulated LIN frame to the signal router 202.If the data field is modified, then it is likely that in order for theframe to still be rendered valid and considered as having no checksumerror by receiving LIN node 110, 120, the checksum need to berecalculated and the checksum field modified as well. No errors areinduced on data link layer. The manipulation can be based on detecting aspecific value of a received identifier, receiving a specific signalvalue in a data field, or a certain bit position in a LIN data frame.The manipulation can be based on a LIN database where position and sizeof a signal in a LIN data field is defined. The first module 281 mayrecalculate a new correct checksum based on the resulting manipulatedcontent of data field, as well as other preceding frame fields that areused for checksum calculation and replace the checksum field.

It is noted that the first bit-stream manipulation module 281 may beimplemented using a full LIN protocol controller in order to decodereceived frames and encode new or modified frames passed on to thesignal router 202.

The second bit-stream manipulation module 291 may optionally becontrolled to modify bits in a data field and a checksum field of areceived LIN frame from the signal router 202 before passing themanipulated LIN frame to the LIN transceiver 201 and the first LIN node100. If data field is modified, then it is likely that in order for theframe to still be rendered valid and considered as having no checksumerror by the receiving first LIN node 100, the checksum need to berecalculated and checksum field modified as well. No errors are inducedon data link layer. The manipulation can be based on detecting aspecific value of a received identifier in an arbitration field,receiving a specific signal value in a data field, or a certain bitposition in a LIN frame. The manipulation can be based on a LIN databasewhere position and size of a signal in a LIN data field is defined. Thesecond module 291 may recalculate a new correct checksum based on theresulting manipulated content of data field, as well as other precedingframe fields that are used for checksum calculation and replace thechecksum field.

It is noted that the second bit-stream manipulation module 291 may beimplemented using a full LIN protocol controller in order to decodereceived frames and encode new or modified frames passed on to the LINtransceiver 201.

Further, only first and second bit-stream manipulation modules 281, 291are shown in FIG. 13. However, the monitoring device 200 may alsocomprise corresponding bit-stream manipulation modules betweentransceivers 211, 221 and the signal router 202, respectively similar to281, 291 also between LIN transceivers 211,221 and signal router 202.While the bit-stream manipulation modules 281, 291 modify thebit-stream, the LIN nodes 100, 110, 120 can be monitored by the LINprotocol handling device 230 as described previously.

The aspects of the present disclosure have mainly been described abovewith reference to a few embodiments and examples thereof. However, as isreadily appreciated by a person skilled in the art, other embodimentsthan the ones disclosed above are equally possible within the scope ofthe invention, as defined by the appended patent claims. Example ofother embodiments are other one-wire or single ended bus systems thanLIN, where at least two bus states exist and using transceivers withother transmitted bus voltage levels and receiving thresholds, and otherdata link layer protocols and other protocol specific events.

Thus, while various aspects and embodiments have been disclosed herein,other aspects and embodiments will be apparent to those skilled in theart. The various aspects and embodiments disclosed herein are forpurposes of illustration and are not intended to be limiting, with thetrue scope and spirit being indicated by the following claims.

1. A method of a monitoring device of monitoring a plurality of LocalInterconnect Network (LIN) buses, wherein at least one LIN node isconnected to each LIN bus, said plurality of LIN buses beinginterconnected via the monitoring device, the method comprising:detecting, for each LIN bus, any dominant data being sent over said eachLIN bus by a LIN node connected to said each LIN bus; and routing saidany dominant data received by the monitoring device over said each LINbus to all remaining LIN buses without overwriting any dominant datasent over the remaining LIN buses.
 2. The method of claim 1, the LINnodes being configured to output dominant data over the LIN buses at avoltage level which is in a first range complying with a requiredtransmit voltage range for dominant data stipulated by LIN standard,while the monitoring device is configured to output dominant data overthe LIN buses at a voltage level which is in a second range complyingwith the required transmit voltage range for dominant data stipulated byLIN standard but which second range is configured to be at a highervoltage than, and not overlap with, the first range, and configured toreceive dominant data at a voltage level at least being in the rangewith which the LIN nodes are configured to output dominant data, whereinthe detecting of any dominant data sent over said each LIN bus by a LINnode comprises: detecting whether a voltage level of data being sentover said each LIN bus is within said first range, in which case a LINnode is detected to send dominant data over said each LIN bus; whereinthe routing of data received by the monitoring device over said each LINbus to all remaining LIN buses comprises: routing the dominant data at avoltage level being within said second range.
 3. The method of claim 2,further comprising: routing, if no dominant data is detected to havebeen sent by a LIN node connected to said each LIN bus and themonitoring device is not sending dominant data, recessive data at avoltage level complying with a required receiver voltage range forrecessive data as stipulated by the LIN standard.
 4. The method of claim2, further comprising, before routing the data to the LIN nodes:encoding, for each LIN bus, the data received over the remaining LINbuses such that an output of the encoding represents dominant data ifany one or more of inputs to the encoding represents dominant data andrepresents recessive data if all inputs to the encoding representsrecessive data.
 5. The method of claim 4, further comprising: encodingthe data received over the LIN buses such that an output of the encodingrepresents dominant data if any one or more of inputs to the encodingrepresents dominant data and represents recessive data if all inputs tothe encoding represents recessive data.
 6. The method of claim 5,further comprising: encoding, the data received over the LIN buses intoone or more LIN protocol symbols; identifying, from the datarepresenting the data sent over the LIN buses, to which one or more ofthe LIN nodes the data being encoded into one or more LIN protocolsymbols belongs.
 7. The method of claim 6, wherein the identifying ofthe one or more of the LIN nodes to which the data representing the datasent over the LIN buses belongs comprises: detecting a start-of-frameindicator in the data representing the data sent over the LIN busesindicating a start of a LIN frame in which the data is to be encoded. 8.The method of claim 1, further comprising: displaying any data monitoredin the monitoring device.
 9. The method of claim 1, further comprising:manipulating data sent over at least one of the LIN buses to cause adesired result on the remaining LIN buses and/or manipulating datareceived over at least one of the LIN buses.
 10. A monitoring deviceconfigured to monitor a plurality of Local Interconnect Network (LIN)buses, wherein at least one LIN node is connected to each LIN bus, saidplurality of LIN buses being interconnected via the monitoring device,which monitoring device comprises a processing unit and a memory, saidmemory containing instructions executable by said processing unit,whereby the monitoring device is operative to: detect, for each LIN bus,any dominant data being sent over said each LIN bus by a LIN nodeconnected to said each LIN bus; and route said any dominant datareceived by the monitoring device over said each LIN bus to allremaining LIN buses without overwriting any dominant data sent over theremaining LIN buses.
 11. The monitoring device of claim 10, the LINnodes being configured to output dominant data over the LIN buses at avoltage level which is in a first range complying with a requiredtransmit voltage range for dominant data stipulated by LIN standard,while the monitoring device is configured to output dominant data overthe LIN buses at a voltage level which is in a second range complyingwith the required transmit voltage range for dominant data stipulated byLIN standard but which second range is configured to be at a highervoltage than, and not overlap with, the first range, and configured toreceive dominant data at a voltage level at least being in the rangewith which the LIN nodes are configured to output dominant data, whereinthe detecting of any dominant data sent over said each LIN bus by a LINnode comprises: detecting whether a voltage level of data being sentover said each LIN bus is within said first range, in which case a LINnode is detected to send dominant data over said each LIN bus; whereinthe routing of data received by the monitoring device over said each LINbus to all remaining LIN buses comprises: routing the dominant data at avoltage level being within said second range.
 12. The monitoring deviceof claim 11, further being operative to: route, if no dominant data isdetected to have been sent by a LIN node connected to said each LIN busand the monitoring device is not sending dominant data, recessive dataat a voltage level complying with a required receiver voltage range forrecessive data as stipulated by the LIN standard.
 13. The monitoringdevice of claim 11, further being operative to, before routing the datato the LIN nodes: encode, for each LIN bus, the data received over theremaining LIN buses such that an output of the encoding representsdominant data if any one or more of inputs to the encoding representsdominant data and represents recessive data if all inputs to theencoding represents recessive data.
 14. The monitoring device of claim13, further being operative to: encode the data received over the LINbuses such that an output of the encoding represents dominant data ifany one or more of inputs to the encoding represents dominant data andrepresents recessive data if all inputs to the encoding representsrecessive data.
 15. The monitoring device of claim 14, further beingoperative to: encode, the data received over the LIN buses into one ormore LIN protocol symbols; identify, from the data representing the datasent over the LIN buses, to which one or more of the LIN nodes the databeing encoded into one or more LIN protocol symbols belongs.
 16. Themonitoring device of claim 14, further being operative to, whenidentifying the one or more of the LIN nodes to which the datarepresenting the data sent over the LIN buses belongs: detect astart-of-frame indicator in the data representing the data sent over theLIN buses indicating a start of a LIN frame in which the data is to beencoded.
 17. The monitoring device of claim 11, further being operativeto: display any data monitored in the monitoring device.
 18. Themonitoring device of claim 11, further being operative to: manipulatedata sent over at least one of the LIN buses to cause a desired resulton the remaining LIN buses and/or manipulate data received over at leastone of the LIN buses.
 19. A computer-readable storage medium storinginstructions that, when executed, cause a processing unit of amonitoring device to monitor a plurality of Local Interconnect Network(LIN) busses, wherein the instructions that cause the processing unit tomonitor the LIN busses comprise instructions that cause the processingunit to: detect, for each LIN bus, any dominant data being sent oversaid each LIN bus by a LIN node connected to said each LIN bus; androute said any dominant data received by the monitoring device over saideach LIN bus to all remaining LIN buses without overwriting any dominantdata sent over the remaining LIN buses.
 20. The computer-readablestorage medium of claim 19, further comprising instructions that causethe processing unit to: manipulate data sent over at least one of theLIN buses to cause a desired result on the remaining LIN buses and/ormanipulate data received over at least one of the LIN buses.